Auditory stimulation during deep sleep enhances total slow-wave activity in a young cohort: A feasibility trial

Cognitive, metabolic and sleep benefits associated with enhancement of sleep slow waves using closed-loop auditory stimulation have been reported in adults but not in adolescents, especially in home settings. Seventeen volunteers (10F/7M; age range: 13-18 years old) participated in a 2-week, single-blind, crossover study. STIM (auditory stimulation ON) and SHAM (auditory stimulation at zero-volume) were each applied for a week (randomized order). Participants used a self-applied, single-electroencephalogram, wearable device at home. An embedded algorithm performed real-time sleep staging, detected slow-wave sleep and delivered auditory tones separated by a 1-s inter-tone interval. After each sleep session, participants completed questionnaires to report sleep quality, sleepiness (Karolinska Sleepiness Scale), and performed tasks to quantify vigilance (Psychomotor Vigilance Task) and working memory (continuous working memory performance task). Sleep architecture, count of microarousals, slow-wave amplitude, total and mean slow-wave activity (electroencephalogram power in the 0.5-4 Hz frequency band) during non-rapid eye movement sleep, sleepiness level, and cognitive performance metrics were compared between STIM and SHAM. The slow-wave amplitude during stimulation, total slow-wave activity and mean slow-wave activity were significantly higher in the STIM condition (+10.7%, +7.38% and + 7.57%). The count of microarousals, and the power in alpha and beta bands were not different between SHAM and STIM. The Pearson correlation between slow-wave activity enhancement and sleep duration (-0.83; p < 1e - 4) suggested a significant decrease in sleep duration proportional to slow-wave activity enhancement. Trending results (p < 0.1) in the STIM condition included higher number of correct continuous working memory performance task responses (+1.01 correct; p = 0.07). This research provides feasibility of auditory stimulation-based slow-wave activity in a young population.